Juvenile criminal law as a branch of law reaches far into the past, to the ancient Greek and Roman period. In the medieval times, on the territory of today's Republic of Croatia, the major documents for juvenile crime legislation were the Dubrovnik, Rijeka and Split Statutes. The first important reform was achieved by passing the fist unified penal code in 1533, named Constitutio Criminalis Carolina, while the precursor of the modern juvenile crime legislation was the Decree of the Civil Governor of Croatia, Slavonia and Dalmatia of 1918. In the period between 1977 and 1997, numerous amendments to the then Criminal Procedure Act were passed, subsequently converted into the Juvenile Courts Act, which regulated the whole matter of juvenile criminal law by means of its material and procedural provisions. The need for reforms in juvenile crime legislation and jurisdiction was evident from the international documents passed by the United Nations, as well as the international conventions aiming at better protection and safeguards guaranteeing the rights fulfillment, while sustaining the wellbeing of the juvenile and protecting their best interest. These are analysed in more detail further in the paper in regard of their importance for modern juvenile crime legislation. Criminal proceedings against juvenile offenders in the Republic of Croatia are regulated by the Juvenile Courts Act. They differ from the criminal proceedings against adult offenders in a number of specific qualities, one of the most important being the purpose of the proceedings, which is sanctioning juveniles through implementation of alternative measures with special preventive impact, recidivism prevention, and help with resocialisation and reintegration. Further in the paper, the attention is focused on the specific qualities of criminal proceedings against juvenile offenders, the principles implemented in the proceedings, the role and tasks of judicial bodies, followed by the course of criminal proceedings, which were analysed in all their procedural phases, with emphasis on the importance of the preparatory procedure. Finally, the influence of European criminal legislature is discussed, as well as its impact on the development of Croatian juvenile crime legislation. In that sense, the Directive (EU) 2016/800 on Procedural Safeguards for Children Suspected or Accused in Criminal Proceedings has an important role. The Directive represents a novelty in the sense of procedural rights protection and establishment of common minimum rules of the rights of suspects and accused persons. Thus the paper assesses conformity of the Croatian Juvenile Courts Act by considering the relevant provisions of the Directive and the solutions offered by the existing Croatian legislation.